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Old October 3rd 07, 06:02 PM posted to rec.aviation.piloting
Bertie the Bunyip[_19_]
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Posts: 3,851
Default Backwash Causes Lift?

Le Chaud Lapin wrote in
oups.com:

On Oct 3, 10:34 am, wrote:
On Oct 3, 8:15 am, Le Chaud Lapin wrote:

Actually I did because every book I read about flying skimped on

the
subject. I'm going to hop over to MIT's OpenCourseWare later this
week and download their most basic course on aero/astro.

Benoulli's
principle is toss around as if it were facecloth, but I'm getting

the
feeling that no one is really doing the physics.


Lemme see: People have been building flying machines since the late
1800's, about 125 years now, and none of them have been interested
enough in the phenomenon of lift to do the physics? How old are you,
anyway? Many of the contributors here have been flying much longer
than you have likely been alive and have studied this in detail, and
some of them might even have doctorates in the subject. The subject

of
lift has been beaten to death on this forum and if you Googled it
you'd find some good information.


I want to be clear. I did not me to say "no one" is doing the
physics. Obviously there are aero/astro scientists all over the
world. What I mean to say is that there seems to be a lot of *pilots*
who are using Bernoulli's principle somewhat carelessly, IMO. Some of
these people are CFI's. Please don't ask me to name individuals, but
I know with certainty that there are at least 2 living, breathing
CFI's who do not understand where 29.92 Hg comes from, or does not
understand it well enough to make it make sense to a student. The
might have understood it at one point, but they don't now. I know
because I asked them. My feelings about teaching is that if you are
not very certain about something, you do more damage than talking
about it. Of course, this leads to the conundrum of having to explain
to a student why a plane stays in the air without providing erroneous
information. If I were a CFI, I would simply say that the aerodynamics
result in pressure below plane is sufficient to counteract pressure
above planes for force of gravity.


That's not enough either.

you need to know how and why lift varies throughot the flight envelope,
but after th ebook learning, it's mostly intuitive and the intuition
comes from experience.

Bertie